NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/physics/23507

Internet Message Format | 1993-01-27 | 9.9 KB

Xref: sparky sci.physics:23507 alt.sci.physics.new-theories:2841 sci.optics:1443 sci.skeptic:22881
Newsgroups: sci.physics,alt.sci.physics.new-theories,sci.optics,sci.skeptic
Path: sparky!uunet!well!sarfatti
From: [e-mail] (Jack Sarfatti)
Subject: Gallis makes breakthrough problem of QM communication.
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: Whole Earth 'Lectronic Link
Date: Wed, 27 Jan 1993 20:11:18 GMT
Lines: 231


Sarfatti responds to:
Organization: Penn State University
Date: Wed, 27 Jan 1993 08:25:46 EST
From: <[e-mail]>
Newsgroups: sci.physics,alt.sci.physics.new-theories
Subject: Re: QM Connection Communication Expt. re-visited.
Lines: 158


>In article <[e-mail]>, [e-mail] (Jack
>Sarfatti)
>says:
>
>Quantum Connection Communication
>I have been taking a fresh look at my gedankenexperiment to achieve
>quantum connection communication by disentangling an entangled state. The
>three mathematical considerations are linearity, orthogonality and
>unitarity. I
                                 *********  *************     *********
>think that some of the initial objections by Gallis and others regarding
>the nonlinearity of my scheme while apparently correct formally were
>actually not ocrrect physically.

>You forgot one of the most important, which is LOCALITY!!!!!

No Mike, I did not forget locality, but I did not include it because Bell's
theorem shows that locality is not consistent with standard quantum
mechanics. Therefore, locality cannot be the reason that standard quantum
mechanics forbids quantum connection communication.

>The mechanisms Sarfatti described in the past have implicitly been of a
>type which are either nonunitary or nonlocal

Agreed.

>(and perhaps both, since the dynamics of the system were never specified
>for general initial conditions).

I never claim that quantum connection communication is a property of
dynamics alone for arbitrary initial conditions - it would be a property of
complex entangled states of many particles.

>My favorite general no communications proof is
>"A General Argument against Superluminal Transmission through the Quantum
>Mechanical Measurement Process"
>by G.C. Ghirardi, A. Rimini and T. Weber
>Lett. Nuovo Cimento V27 p293 (1980)

>There has been a more recent follow up article, but I do not have that
>reference handy.

Please post the precise reference when you find it.

>This article shows that linear, local and probability conserving evolution
>cannot permit FTL communication.

I have no problem believing that! Of course if it is local there is no FTL
communication. That's a red herring since standard QM is not local. If they
put in locality then their proof is totally irrelevant to the actual
problem!

I agree that my toy model is "nonlinear" in the sense that you use the term
"linear". But my model does conserve probability. So my model is, in your
terms, nonlinear, nonlocal and probability-conserving.

>(Note that nonunitary evolution is also accounted for in this proof.)

I do not think what you say here is really relevant since if they assume
locality to start, locality by itself is enough to destroy FTL
communication. Therefore, it is trivial that non-unitary evolution does not
matter in their scheme. But, again, you cannot start with locality if you
are doing standard quantum mechanics or even some non-standard quantum
mechanics that limits to standard quantum mechanics.

>The mathematical formalism of density operators and dynamical semigroups
>is used, so that the proof is more general than the usual state vector
>approaches.  This allows for dissipation effects and other nasties to be
>accounted for in a rather general manner.

This approach without the initial assumption of locality would be decisive,
I agree. Are you sure they start by assuming locality? That seems stupid
and I don't think they are stupid.

>I suggest that you read this article and endeavor to understand it before
>persisting with unending variations of this nonsense.

I will read it if you can tell me where to find it.

>Here is the basic point regarding the linearity objection. In Fig.1,
>imagine two Stern-Gerlach magnets. One splits the beam, the other
>reconstructs the initial state.
>
>               _________________ |+>__________________
>  |i>         /                                       \              |i>
>------------/                                           \_______________
>            \                                           /
>              \_________________ |->__________________/
>
>Fig.1
>
>|i> = |+><+|i> + |-><-|i>
>
><+|-> = 0
>
>               ___________________ |+>______________
>  |i>         /                                     \                |f>
>------------/                                         \_________________
>            \            __                           /
>              \____|->__|U |______ e^i@|+> = U|->____/
>                        |__|
>
>Fig.2
>
>In Fig.2, a spin-flip coil U is put in only one path. The second Stern-
>Gerlach magnet is modified in design so that the two sub-beams are
>recombined to one beam. This should be possible. I think a similar
>experiment has actually been done with neutrons and neutron
>interferometers. The output state |f> is no longer the same as the initial
>state |i>. Assuming that the spin-flip does not correlate to orthogonal
>number states of the radiation oscillator but, rather, to non-orthogonal
>coherent Glauber states, we can write
>
>|f> = |+><+|i> + U|-><-|i>
>
>    = |+><+|i> + e^i@|+><-|i>
>
>    = |+>[<+|i> + e^i@<-|i>]
>
><i|i> = <f|f> = 1  implies
>
><+|i><i|->e^-i@ + <-|i><i|+>e^i@ = 0
>
>This is obviously physically correct, yet it "formally" appears to violate
>linearity in that Gallis and others apparently insist upon wanting to
>write that
>
>|f>' = U|i> = U|+><+|i> + U|-><-|i> = e^i@(+)|-><+|i> + e^i@(-)|+><-|i>
>
>which seems obviously physically wrong to me.

>Sarfatti has demonstrated in past posts a gross misunderstanding of
>quantum mechanics, Feynman path integrals and elementary linear algebra.
>Do not take his intuition too seriously (at least not without some
>formal training...)

Tut, tut, Mike - flames!

>The math is nonsense not because the math is wrong, but because the
>physics is wrong.  The apparatus contains a segment which looks like
///
>
>               ___________________ |+>____________
>  |i>         /
>------------/
>            \            __
>              \____|->__|U |______ e^i@|+> = U|->
>                        |__|
>
 from your Fig.2

>From the standpoint of optics, this makes sense, essentially there
>are two componments, a beam splitter ( a birefringent crystal, prhaps)
>and a component which rotates the polarization (a quarter wave plate?).
>HOWEVER,there is also the part which looks like


>                                   |+>______________
>                                                    \                |f>
>                                                      \_________________
>                                                      /
>                                   e^i@|+> = U|->____/
>
>
>also from your Fig.2

>This element is the bogus physics.

OK, Mike, now where are making progress. You are about to make a valuable
contribution. I wish you had stated it months ago! We could have save a lot
of time. But better late than never! How about "wrong" rather than "bogus".
"Bogus" implies intent to deceive and I have no such intent.

>In order for it to work, one must be able to get two photons of identical
>polarization coming in from different directions with the same
>polarization, but perhaps with a phase difference to emerge from the
>device in the same direction.

Yes, Mike that's right, that is my idea for this particular model.

>Classically, this device must take two beams of light with identical
>polarizations, and which vary by a phase, which are coming from two
>different directions and deflect one or the other or both so that they
>emerge in exactly the same directions.   In order for this to happen one
>needs to come up with a material which has an index of refraction which
>depends upon this phase, and this just doesn't exist.

OK, Mike, I admit, that if you can really prove this last remark then this
particular model will not work for the reason you say. So please give a
clear proof and I will admit defeat for this attempt. But notice, the
device allegedly fails for a subtle reason - not on general grounds of
locality etc. But if your proof depends upon locality or dispersion
relations then I will not buy it. However, you have made a valuable
contribution in any case because you have spelled out a necessary property
of the material for the beam recombiner that is necessary for this kind of
quantum connection communication to exist.

>Now, Sarfatti could just bury this issue in smoke by using non-orthogonal
>states in the discussion. It's the type of thing which has happened before
>and will probably happen again (the obfuscation in irrelevant detail, not
>necessarily the particular technique).  It would go a long way towards
>legitimizing his arguments if he would design (with specific real
>components,cost is no object) an apparatus which could  presumably do what
>he claims (items such as this beam recombiner would be the most crucial).
>No Fantasy Apparatus allowed.

>In previous posts, mathematical arguments have been used to argue
>(to prove) that Sarfatti's description was unphysical.  This is one
>of the strong points of mathematical formalism.  I do not believe
>that anyone had pinpointed Sarfatti's actual point of departure
>(from real physics/real life) using formalism alone.  This may be a weak
>side of "mere formalism".  However, what remains is that the
>formalism works, but the device will/can not.

> mike gallis
>the apparant villain of Sarfatti's post.

Quite the contrary, Mike you and Aephraim Steinberg have made valuable
contributions and it will be so noted by Star Fleet Command. Indeed, I will
provide you with a grant at some future date - same to Aephraim.